Add Andrei Ushakov to Contributors list

Created by: aushakov95

Contributors.md

+- [Andrei Ushakov](https://github.com/aushakov95)
 - [Zakaria Soufiani](https://github.com/zakaria-soufiani)
 - [Eduard Barata](https://github.com/bar-alex)
 - [Richard Placide](https://github.com/richardplacide)